Typewriting-machine



Mfnessex L. S. BURRIDGE, DECD. r. 0. sunmnes, EXECUTOR. TYPEWRITINGMACHINE.

APPLICATION FILED DEC.3,1917.

Patented Sept. 7, 1920.

2 SHEETSSHEET l- L. S. BURRIDGE, DECD. F. 0. BURRIDGE. sxzcuroa.TYPEWRITING MACHINE.

APPLICATION FILED DEC. 3, 1917.

PatentedSept. 7, 1920.

2 SHEETS-SHEET 2.

l Vhnesses:

' movement by a s ring which counteracts the a UNITED STATES PATENTOFFICE.

LEE s. BURRIDGE, DECEASED, LATE or NEW YORK, N. Y., BY rEANcis -o.BURRIDGE,

EXEGU'IOR, or NEW YORK, N. Y., AssIeNoE, BY MESNE ASSIGNMENTS, TO UNDER-woon TYPEWBITEB COMPANY, or NEW YORK, N. Y., A CORPORATION or DELA- ARE.

TYPEWRITING-MACHINE.

Specification of Letters Patent.

Patented Sept. 7, 1920.-

Original application filed September 27, 1915, Serial No. 52,594.Divided and this application filed Decemher 3. 1917. Serial No. 205.109.

March 11, 1919).

An object of this invention is to provide a simple and positiveback-space mechanism which may be economically manufactured and easilyassembled,

In the type of machine illustrated, the platen carriage is mounted upona frame which is shiftable up and down to various positions forpermitting the printing of different case-types. .This shiftable framecomprises front and back sheet-metal plates. An escapement wheel,mounted between these front and rear plates, is controlled by fixed andloose dogs. These dogs are alternately shifted by the depression ofthe-keys of the machine into and out of cooperative relation with theescapement wheel to permit the letter-feed movements of the typewritercarriage under the influence of a propelling spring. When a key isdepressed, the loose dog, which normal y engages one of the teeth of theescapement wheel, is-

withdrawn therefrom and moves under the influence of a spring, connectedto said dog, into a position in which'it will be engaged by the nextsucceeding tooth when returned to the esca ement wheel. Before the loosedog'is free from the escapement wheel the fixed dog engages andtemporaril holds said wheel. he loose dog is limite in this actions ofthe ot er spring connected to the do when the dog reaches a properposition toie engaged by the next sucoeedin tooth.

In the present invention, a bat: -space pawl, controlled by a back-spacekey at the keyboard of the machine, directly engages.

the escapement wheel'to move the same in a reverse direction, and theescapement wheel,

- being positively geared to the carriage,

cause the escapement Wheel has been prevented from rotating in reversedirection by the escapement dogs. Therefore, the backspace mechanismcould not operate upon the carriage through the escapement wheel.

In the present invention, however, it is possible to back-space thecarriage by rotating the escapement wheel in reverse direction, becauseof the fact that the escapement dogs permit the backward rotation of theescapement wheel, and therefore, the escapement wheel can be positivelgeared to the typewriter carriage. It wil be seen that this arrangementof back-spacing the carriage, through; the escapement wheel, isverysimple and makes it unnecessary to provide numerous additionalparts.

The back-space pawl ma be pivotally mounted upon an arm which has aswingmg movement about the axis of the escapement wheel. The back-spacekey may be pivotally mounted on a bracket secured to the main frame ofthe machine and have a P01111011 engaging an arm of a bell-crank, whichis also mounted on the main frame and which has a link connection to thearm carrying the back-space pawl. In order that the depression of theback-space key may impart a longitudinal motion to the pawl-carryingarm, the axis of the bellcrank is arranged at substantially right anglesto the axis of the backspace key. The bell-crank is preferably arrangedat a considerable distance from the pawl-carrying arm, so as to permitthe case-shifting movements of the latter, which is mounted on theshiftable frame, without interfering with the operation of theback-space mechanismwhile the frame is in any case-position.

The back-space pawl is normally held out of engagement with theescapement wheel by engagement of an arm carried by said pawl with afixed stop, arranged so that a spring connected to the pawl moves thecapement wheel, at the very beginning of the downward movement of theback-space key. The continued movement of the backspace key causes thepawl to drive the escapement Wheel back a distance equivalent to twoletter-space movements of the carriage, which allows one tooth of theescapement wheel to pass the loose dog and move to position to engagethe loose dog when the back-space key is released. This "causes thecarriage to be moved back two letter-spaces and when released to be freeto move under the carriage-spring influence one letterspace to properposition.

If the operator desires to insert a character at a place twoletter-spaces back from that occupied by the typewriter carriage, theback-space key is depressed and kept depressed by the finger while theomitted character is being printed. However, when the operator desiresto reset the carriage only one letter-space distance, the back-space keyis fully depressed and then released before the type-key is operated.

Other features and advantages will hereinafter appear.

In the accompanying drawings,

Figure 1 is a side elevation, showing the platen, the platen-carriageand the platencarriage-shift-frame.

Fig. 2 is a sectional side elevation, showing the escapement mechanism.

Fig. 3 is a rear elevation, showing the escapement mechanism and theback-space mechanism.

Fig. 4 is a sectional side elevation, showing the escapement yvheel andthe mounting for the back-space pawl.

Fig. 5 is a front elevation, showing the escapement mechanism, theback-space-pawl and-the connections from the back-spacepawl to theback-space-key.

Type-bars 10 swing upwardly and rearwardly against the front face of aplaten 11, at the depression of keys 12 mounted on key-levers 13. Theplaten 11 is mounted on an axle 14 rotatably mounted in side plates 15,forming part of a typewriter carriage 16;.said carriage also comprisestransverse bars 17 serving as rails for ball-bearings 18, upon' whichthe carriage rides in letter-feed and returndirections. The ballbearingsare confined between the rails 17 and forward and rearward plates 19 and20 which form part of a frame 21. The

frame 21, which also comprises side plates 22, is suitably guided andshiftable substantially vertically for the purpose of moving the platento various case-printing positions.

The typewriter carriage 16 normally tends to move in letter-feedingdirection, under the influence of a spring drum 23 connected by a cordor tape 24 to the typewriter carriage. The letter-feed movement of thetypewriter carriage is controlled by an escapement mechanism whichcomprises an escapement wheel 25 and also a pinion 26, secured thereto,engaging with a rack 27 carried by the carriage. The escapement wheel ismounted to rotate on a pin 28 which is removably mounted in bushings 29and 30, secured to the front plate 19 and the: rear plate 20,respectively. The pin 28 is secured to a plate 31 which is held in placein the machine by being secured to the rear plate 20 by a screw 32. Theescapement wheel 25 is confined on the pin 28 between the bushings 29and 30. The escapement wheel 25 is normally prevented from rotating,under the influence of the carriagespring 23, by an escapement dog 33which engages with one of the teeth 34 of the escapement wheel. The dog33 is pivotally mounted at 35 upon a plate 36, and has its movement inone direction limited by a stop-pin 37 secured to the plate 36.

fore. the escapement dog 33 is normally held against the stop-pin 37.The plate 36 is mounted for rocking movement on trunnions 38 whichextend through ears 39 in a bracket 40 secured to the rear plate 20. Therocker plate 36 is provided with connections to a universal bar 41arranged directly beneath, and operated by, the keylevers 13. Theseconnections comprise a floatingly-mounted draw-bar 42 engaging therocker plate 36 which is operated by an arm 43 carried by a rock-shaft44 having arms 45 connected by links 46 to the universal bar 41.

When the key-lever 13 is depressed and the rocker plate is operated, theloose-dog 33 is moved out of engagement with the tooth 34v of theescapement wheel, and a fixed dog 47 is'moved into engagement with saidwheel, to hold the same temporarily against movement. Thus freed fromthe escapement wheel, the loose dog 33 is moved up toward the next toothon the escapement wheel by a spring 48, connected to an arm 49 extendingrearwardly from said dog, into theposition shown in dot-and-dash linesin Fig. 3. In this position the dog 33 is located opposite the nexttooth. When the rocker plate is returned to normal position by itsspring 50 (see Fig. 2), the fixed dog 47 is moved out of engagement withthe escapement wheel, and the loose dog 33 is moved into position to beengaged by the next tooth on the escapement wheel. After being releasedby the fixed dog 47, the escapement wheel rotates under thecarriagespring influence until the said next tooth 34 strikes the dog 33and moves the same against the tension of its spring 48 until the loweredge of the dog is arrested by the stop 37 on the rocker plate 36. Thiscauses the carriage to move one space in letter-feed direction. Theloose dog 33 is limited in its upward movement to the dot-and-dash lineposition, shown in Fig. 3, by a spring 51-. This spring 51 tends tooppose the action of the spring 48,"'when the loose dog has moved to thepro r yieldingly hold said 0g.

key 52 on a lever 53, pivoted at 54 to a bracket 55 on a cross-piece56in the main frame. The lever 53, when depressed at its forward end,engages at its rearward-end and moves an arm 57 of a bell-crank '58pivoted at'59 on a bracket 60, also on the main frame. The bell-crank 58is held in normal position by a spring 61. The other arm 62 of thebell-crank 58 is connected by a link 63 to an arm 64, whichis mounted torotate about the axis of the escapement wheel 25. The arm 64 has'pivotally-connectedthereto at 65 a drive pawl 66 having a nose 67arrangedto en age the teeth 34 of the escapement wheel. he drive pawl 66is preferably made of sheet-metal and has a bent-off portion which formsthe nose 67. The pawl normally tends to move into engagement with theescapement wheel, under the influence of a spring 68 having one endconnected to an arm 69 on the pawl-carrying lever, and its other endconnected to a bentoff portion 70 on an arm 71 formed integral with thedrive pawl 66. The pawl 66 is normally held out of engagement with theescapement teeth, against the tension of the.

spring 68 by a projec tion or guard 72 with which the bent-off portion70of the pawl engages.

At the first portion of the downward movement of the back-space-key 52,the link 63 is moved to the left, as seen in Fig. 5, to rock thepawl-carrying arm 64 suflicient to permit the bent-ofi' portion 7 O ofthe pawl 66 to move away from the guard 72 under the influence of itsspring 68, so as to bring the nose 67 of the pawl into engagement withone of the teeth 34 of the escapement wheel. The continued downwardmovement of the back-space key causes the pawl-carrying arm- 64 to drivethe pawl, and the pawl, in turn, to drive the escapement wheel toback-space the typewriter carriage.

As the-escapement wheel is moved in re verse or anti-letter-feeddirection, under the control of the back-space pawl 66, the tooth 34 ofthe escapement wheel, which is located beneath the escapement dog 33, asseen in Fig. 3, is moved upwardly. This causes said tooth to cam theloose-dog 33 upwardly against the tension of the dog-controllingspring51, until the dog has been cammed to l position, and'thus writercarriage to be moved back two letter- The back-space mechanism comprisesa ment wheel may pass the same, and in which spaces. This movement oftwo letter-spaces permits the tooth of the escapement wheel to engageand move the loose escapement dog and move past said dog sufficiently topermit the dog to moved by its spring into a position shown in Fig. 3,in dot-anddas'h lines. In this position the loose escapement dog will beengaged by the tooth ofthe'f'escapement wheel and moved under theinfluence of the carriage, when the backspace key is released, until thedog strikes its fixed stop 37, which will arrest the carriage at oneletter-space distance from the point at'which the back-spacing operationwas commenced. Y

The back-space key when released is returned to normal position by thespring 61. This spring also returns the pawl-carrying arm 64 with thepawl 66. The teeth 34 of the escapement wheel are so shaped as to causethe nose 67 of the pawl 66 to be cammed out and pass said teeth duringthe return movement of the pawl. The pawl is finally held out ofengagement with the teeth of the escapement wheel by the guard 72,

against which the bent-portion 70 on the pawl 66 ;strikes-.-- Thiscauses the pawl to swing about its pivot "65, so as to withdraw the nosefrom the teeth ofthe escapement wheel against the tensionof the spring68. To permit the back-space key to operate the pawl-carrying arm in allcase-positions of the platen frame on which the pawl-cartance betweenthe bell-crank and the pawlcarrying arm is such that the variation ofthe angular position of the link in no way affects the operation of theback-space mechanism.

For convenience in assembling the device, the pawl-carrying'arm 64 ispivotally mounted upon the bushing 30, which, with the bushing 29,serves as a support for the pin 28 on which the escapement wheel ismounted. In assembling the device, the pawl- .earrying arm may beslipped upon the bushing 30 before the'escapement wheel is placed inposition. If it is desired to remove the pawl-carrying arm for thepurpose of re-' pairs, the pin 28 may be withdrawn from the bushings 29and 30, and the escapement wheel temporarily removed to permit thewithdrawal of the pawl-carrying arm 64 from the bushing 30.

If the operator desires to print a character two letter-spaces back fromthe position occupied by the carriage, the back-space key is depressedand held depressed during the printing operation; for it will beremembered that the back-space key, when depressed, moves the typewritercarriage back two spaces, so that, when released, the carriage will bearrested at the proper place by the escapement dog. Therefore, if theback-space key is maintained depressed, the carriage will be located twoletter-spaces from the position previously occupied.

Variations may be resorted to within the scope of the invention, andportions of the improvements may be used without others.

Having thus described the invention, the claims are:

1. In a typewriting machine, in combination, a platen-carriage,letter-spacing mechanism therefor, including an escapement wheel andmechanism cooperating therewith to control its movements in normalletterfeeding direction, said wheel and controlling mechanism being sorelated as to permit a back-spacing rotation of said wheel in thereverse direction, and back-spacing mechanism for said wheel, comprisinga back-spacing pawl, a' movably mounted pawl-carrier therefor, meansnormally tending to move said pawl relatively-to said carrier to aposition such as to engage a tooth of said escapement wheel, a stopfixedly mounted on said carriage, an abutment on said pawl, normallyheld in engagement with said stop, and preventing'movement of said pawlto its tooth-engaging relation, and means for moving said carrier so asto separate said abutment from said stop, to permit said pawl to bemoved into tooth-engaging relation with said escapement wheel, androtate said wheel in a reverse direction, to an extent such as to bringa different tooth of said escapement wheel into position to be engagedand held by said controlling mechanism.

2. In a typewriting machine, the combination with' a platen, ofmeansincluding a carriage for feeding the platen in letterfeed direction, andmeans for effecting a step-by-step movement of the platen carriage inthe opposite direction, comprising a toothed member connected to thetypewriter carriage, a pawl adapted to engage said toothed member, meansincluding a movable pawl-carrier for causing the pawl to engage and movesaid toothed member, said carriage being shiftable bodily up and downtogether with said carrier, a bell-crank to which said carrier isdirectly connected by a single link, said bell-crank beingmounted on thestationary framework, and a key-lever arranged to directly engage androck the bell-crank.

3. In a typewriting machine, the combination with a main frame, of aplaten frame shiftable bodily between case positions on the main frame,a platen, means on the platen frame for feeding the platen inletter-feeddirection, and mechanism for effecting a step-by-stepmovement of the platen in the opposite direction, comprising a toothedwheel on the shiftable platen frame, a pawl adapted to engage saidwheel, a movable carrier for said pawl, said pawl and carrier beingshiftable together with said platen frame, and means for causing thepawl to engage and move the wheel, said means including a link directlyconnected to said carrier, and means on the stationary main frame fordirectly engaging and actuating said link, said link being so arrangedas to vibrate to permit the case-shift movements of said pawl andcarrier with said platen frame, without interfering with the operationof said pawl in all case positions of the platen frame,

4. In a typewriting machine, in combination, a frame, a platen-carriageshiftable to different case positions relative to said frame,letter-spacing mechanism therefor, including an escapement wheel andmechanism cooperating therewith to control its movements in normalletter-feeding direction, said wheel and controlling mechanism beingmounted on said shiftable platen-carriage, and so related as to permit arotation of said wheel in the reverse direction, and back-spacingmechanism for said wheel, comprising aback-spacing pawl, a movablymounted pawl-carrier therefor, said carrier being mounted on saidshiftable platen-carriage, and means for causing said pawl to engage atooth ofsaid wheel to impart a reverse rotation thereto, saidpawl-operating means including a relatively long link extendingtransversely of the machine, said link being connected at one end tosaid pawlcarrier, and 1 a key-controlled operating mechanism mounted onsaid frame and connected directly to the other end of said link, so thatthe movement of said pawl and carrier fromone case position to anotherwith said platen-carriage may cause a swinging movement to be impartedto said link, While preserving the cooperative relation between saidkey-controlled operating mechanism and the back-spacing pawl andcarrier.

FRANCIS O. BURRIDGE, Executor 0f the last will and testament of Lee S.Bwm'dge, deceased.

' Witnesses:

CHARLES W. HOWELL, ARTHUR A. JOHNSON.

